On Mon, 22 Aug 2005, Alex van den Bogaerdt wrote:
Pobox is right to check. They are NOT false rejects.
The problem is that small businesses like all my clients typically
have only one "choice" for broadband ISP (the local DSL or cable monopoly).
Typically, that ISP is completely incapable of properly assigning or
forwarding PTR records. If you are lucky, they assign some generic PTR in the
ISPs domain (which passes the PTR test - but provides no meaningful
identification). But usually, you either get no PTR at all, or a PTR to some
random name with no A record. No amount of phone calls can change this. The
only solution has been to relay outgoing mail through another system lucky
enough to have working PTR records (with accomanying complexities of adjusting
SPF records, SMTP AUTH, yada, yada).
The PTR test is inherently unfair, because it is simply not possible
for an MTA to comply with it in general. PTR is under the control of the ISP,
*not* the mail sender. By blocking mail with bad PTR, you are
essentially requiring that all your senders have competent ISPs, or
be big enough to buy a full sized IP block.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.